Plaster applying apparatus



July 3, 1962 1 H. HoBsoN PLASTER APPLYING APPARATUS 2 Sheets-Sheet l Filed Oct. 13, 1960 July 3, 1962 L, H. HoBsoN 3,042,316

PLASTER APPLYING APPARATUS Filed Oct. 13, 1960 2 Sheets-Sheet 2 7] Nl-1|. dal@ la@ 7 77 75 l United States Patent 3,042,316 PLASTER APPLYENG APPARATUS Lloyd H. Hobson, Lernout, lll., assigner to Plastering Development Center, Inc., Chicago, Ill., a corporation of Illinois Filed Giet. 13, 196i), Ser. No. 62,461 10 Claims. (Cl. 239-415) This invention relates `to plaster applying apparatus and, more particularly, to apparatus for applying plaster to wallboard and the like.

The instant application provides a novel apparatus in the form of a gun type applicator and which is useful in connection with the method of applying plaster set forth in my copending application, Serial No. 6,8l4, led February 4, 1960. Reference may be had to my earlier application for details of operation not given here.

In the aforementioned application, a method of applying plaster is set forth in which an accelerator material is incorporated into a flowing stream of plaster just prior to the application of the plaster to a wallboard or other surface. The instant application discloses a nozzle-type gun in which means are provided for introducing an accelerator material into a owing stream of plaster and the provision of such constitutes an important objective of this invention.

Another object of this invention is to provide a novel plaster applying system in which pressurized cernentitious or like material of relatively slow set is forced through an applying device and `just before exiting therefrom is mixed with a material accelerating the set, and in which novel means is provided for maintaining the applying device free of the quick setting material.

A further object is to provide a plaster applying appa ratus in which a novel sequence of valve and control operations is achieved which insures against the obstruction of the various material feed lines. Other objects and advantages can be seen in the details of construction and operation set down in this specification.

The invention is explained in conjunction with the accompanying drawing, in which- FIG. l is a schematic diagram of the apparatus of the invention, with portions thereof in section;

FIG. 2 is an enlarged elevational View, partially in section, of the nozzle-equipped applying means or gun shown scehmatically in FIG. l;

FIG. 3 is a fragmentary sectional view of the apparatus seen in FIG. 2 and with the operative elements thereof in the same position;

FIG. 4 is a view similar to FIG. 3 but with the operative elements in a dierent condition, corresponding to slifht retraction of the applicator gun trigger;

FIG. 5 is a view similar to FIGS. 3 and 4 but differing therefrom in showing the operative elements in yet another condition, corresponding to substantial retraction of the trigger; and

lFIG. 6 is a View similar to FIGS. 3-5 but in which the operative elements are in yet another condition, conresponding to full retraction of the trigger of the plasterapplying gun.

In the illustration given, and with particular reference to FIG. l, the numeral 10 designates generally a reservoir or hopper of plaster which has been combined with water in suitable quantity to make the stream ilowable. Fluid plaster from the hopper 1G is pumped therefrom by means of a pump 11 into a conduit 12. The conduit 12 leads to a gun or plaster-applying device 13 equipped with a nozzle 14. Also communicating with the gun 13 is a second conduit 15 which leads from an air compressor 16. Intermediate the air compressor 16 and the gun 13, the conduit 15 is equipped with a Venturi 17. Communicating with the interior of the conduit 15 at the Ven- Mice turi 17 is a subconduit 18 leading to a tank 19. The tank 19 is lled with an accelerator material, and the reduced pressure in the Venturi fitting 17 is eective to aspirate iiuid from the tank 19 through the subconduit 18 into the main conduit 15.

The air from compressor 16 may also flow through conduit 20. As shown, the conduit 15 is equipped with a branch conduit 2t) intermediate the compresso-r 16 and the Venturi 17. The conduit 2li leads to a chamber 21 and from the chamber 21 to the spray gun 13. The chamber 21, in the illustration given, is a cylinder equipped with an internal piston 22. The piston 22 is equipped with a piston rod 23 and is normally urged upwardly by means of a spring 24. The conduit line 20 is connected to the cylinder 21 as at 25, a constricted orice b-eing provided at 25. Air may issue from the chamber 21 via the line 26 and thus reach the gun 13. The piston rod 23 at its lower end, as at 23a, is coupled to a switch on the pump switch (not shown) on the pump 11, depression of the piston 22 serving to start the pump 11, while elevation of the piston 22 under the urging of the spring 24 results in stopping the pump 11.

Referring now to FIG. 2, the gun 13 can be seen in greater detail and is seen to include a barrel portion generally designated 27 and a handle portion generally designated 28.

The handle portion 28 includes a generally T-shaped body 29 equipped with an inclined passage 30 for the flow of plaster or other cementitious material delivered to the gun 13 by the conduit 12. The `body 29, at its lower end as at 31, is equipped with a fitting 32 which couples the end 31 with the conduit 12. The passage 30 terminates in the nozzle 14 and intermediate the inlet end 31 and nozzle outlet 14 of the passage 30, the passage 311 is equipped with a valve generally designated 32. [For this purpose, the passage 30 is enlarged as at 33 and tted therein is an apertured plug member 34. rl`he plug member 34 is equipped with a central aperture or passage 35 which is flared outwardly as at 36 to provide a valve seat. The upper portion of the body 29 is bored as at 37 in alignment with the upper branch of the passage 3d and slidably mounted in the bore 37 is a valve stern 38. At its extreme bored end, the valve stem 33 is equipped with a rubber cap 39 which cooperates with the valve seat 36 in providing the valve 32. In the illustration given, the cap 39 is secured in axial relation ywith the valve stern 38 by means of a bolt 4t). Suitable O-ring seals as at 34a may be interposed between the plug member 34 and the forward end of the body 29 to insure lealproof operation of the passage 3).

An end cap 41 is mounted against the forward end of the body 29 by means of a bracket 42. The end cap 41 is centrally apertured as at 43 to provide a mounting for the nozzle 14. Again, an O-ring seal. 44 is installed to insure leakfproof operation. The end cap 41 is equipped with an annular chamber 45 which is in communication with the plaster flow passage 30 between the valve 32 and the nozzle 14, an apertured sleeve 46 being installed between the nozzle 14 and the element 34 and in coaxial alignment therewith. The sleeve 46 is equipped with apertures or flow ports 46a.

The end cap 41 is equipped with a passage 47 cornmunicating with the chamber 45 and extending generally parallel with the upper portion 30a of the L-'shaped piassage 30. The lbody 29 is equipped with a passage 43 which is aligned with and communicates with the passage 47. It will also be noted that the extreme upper portion of the body 29 provides a pivot mounting 49 for the pivot 5t) which is provided as part of the trigger 51.

The rear portion of the barrel 27 is provided by tubular portions generally designated 52 and 53 which are mated along the line of contact 52a, the portion 52 being mated with the body 29 along 52h. It will be seen that the conduit communicates with the tubular portion 52 by means of the litting '54, while the air conduit 26 communicates with the portion 53 by means of the fitting 55. Both tubular portions 52 and 53 are equipped with aligned, communicated bores or passages 56 and 57, respectively, the passage 56 extending all the way through portion 52. The tubular portion 53 is equipped with a branch passage 58 which provides an inlet to the passage 57 for the control air which issues from the chamber 21 as through the port 25a.

In similar fashion, the tubular portion 52 is equipped with a branch passage 59 which serves as an inlet to the passage 56 for the atomizing or aspirating air led to the gun 13 by the conduit 15 from the Venturi 17.

The tubular portion 52 is equipped with an annular -chamber 60 which serves to communicate the longitudinal passage 56 with the longitudinal passage 61. The passage 61, as can be readily appreciated from a consideration of FIG. 2, is aligned with and communicates with the passages 48 and 47. In this connection, annular sleeves 62 and 63 may be employed in conjunction with O-rings 62a and 63a in order to insure fluid-tight lits between the elements 52 and 29, and 29 and 41, respectively.

The passage 56 is equipped with three spaced-apart constricted portions 64, 65 and 66. The constricted portion 64 provides a shoulder 67 against which a coiled spring 68 is mounted. The spring 68 bears against a plate 69 provided at the rear end of the valve stem 38. The Valve stem 38 is equipped with a recess 70 in which a pin 71 is slidably mounted. The pin 72, as can be seen from the dotted line connection on FIG. 2, is provided as part of a lost mot-ion linkage extending rearwardly `from the trigger 51. Thus, upon retraction of the trigger 51, the pin 71 moves rearwardly a distance until it abuts the shoulder 70a defining the rear of the notched-out portion 70. Thereafter, further retraction of the trigger 51 will result in movement of the valve stem 38 rearwardly, with the consequent removal of the rubber end cap 39 from the valve seat 36. This, then, communicates the inlet and outlet of the passage 30, and, when the pump 11 is energized, will permit flow of fluid plaster through the gun 13 and out of the orifice 14.

Still referring to FIG. 2, it will be seen that the first constricted portion 64 provides `a bearing for a sleeve valve 72. The sleeve valve 72 extends forwardly, i.e., toward the nozzle 14 and `axially within the coiled spring 68. At its extreme forward end, the sleeve valve 72 is equipped with a plug fitting 73. The plug fitting 73 is seen to be in contact with the pin 71. Thus, retraction of the trigger 51 initially moves the slide valve 72 rearwardly, that is, prior to the opening of the plaster valve 32.

Adjacent its rearward end, the sleeve valve 72 is mounted in a washer 74 which is interposed between the tubular portions 52 land 53. The washer 74 retains the U-cup seal 74a which lbears against the sleeve valve 72. The portion 72a of the sleeve valve 72 within the bore 57 is equipped with an annular plate or flange 72b. Extending between the flange 72b and the extreme rear wall 75 of the bore 57, is a coiled spring 76. The effect of the coiled spring 76 is to urge the lsleeve valve 72 forwardly and into contacting relation with the pin 71. Thus, both the springs 76 and 68 serve to urge the trigger S1 forwardly.

The sleeve valve 72 is equipped with two sets of apertures 77 and 78, permitting fluid which enters the end 79 of the valve 72 to flow into the chamber 60 when t-he valve 72 is in the position illustrated in FIG. 2.

The chamber 60 is equipped with an apertured sleeve fitting 80 which is supported l.between ring seals 81 and 82, the ring seals 81 and 82 providing sliding seals for the slide valve 72. In like fashion, the chamber 83 which communicates with the atomizing air inlet 59, is equipped with an apertured sleeve 84, supported between ring seals 85 and 86. It will be noted from an inspection of FIG.

2 that the ring seals 86 and 81 are supported on the annular constriction 65, while the ring seal 8S is supported upon the constriction 64. The tubular portions 52 and 53 are maintained in fluid-tight connection both with themselves and with the body 29 by means of a tie rod 86 equipped with a suitable locking nut 87.

It is believed that the invention can be more Afully appreciated from a consideration of the operation thereof, and, for that purpose, such a description is set down below.

Operation Stand-by condition of the gun 13 is seen in FIG. 2, and, in more fragmentary form, in FIG. 3. Reference to FIG. 3 reveals that the sleeve valwe outlets 77 and 78 are positioned in alignment with the chamber 60 so that only control air from the conduit 26 is permitted to flow through the aligned passages 61, 48 and 47 to the chamber 45 and thence out of the nozzle 14. This control air is provided by the compressor 16 and issues therefrom through the conduit 16a to the branch conduit 20', and then to the chamber 21. Inasmuch as the flow of control air is restricted by the provision of the orifice 25, only a small amount of air flows through the upper portion of the cylinder 21 (see FIG. 1) and eventually out of the port 25a and through the gun 13. This amount of air is insufiicient to bias the spring 24 so that the piston 22 is at the upper end of its stroke, which means that the pump 11 is shut down. However, even the provision of the small amount of air is effective to purge the sleeve 46 and nozzle 14 of any plaster, and this is particularly significant since plaster in either of these elements would tend to set rapidly. For example, the plaster provided in the hopper 18 ordinarily will have a two hour set time, achieved through the use of a suitable retardant. The accelerator, which is introduced through the line 15, will change the set time to 10 minutes or less, as desired. Thus, even a temporary shutdown of the plaster stream would result in deposit of a quick-setting plaster material in and about the nozzle 14 which would tend to clog and prevent further operation of the gun 13. This is effectively removed through the maintenance of the control air stream flow which simultaneously cooperates in shutting7 down the pump 11.

When it is desired to initiate the application of plaster, the trigger 51 is pulled or retracted, i.e., moved to the left in FIG. 2. Slight movement of the trigger 51 produces a corresponding movement of the linkage system terminating in the pin 71, the pin 71 moving rearwardly and forcing with it the sleeve valve 72 against the urging of the spring 76. A comparison of FIGS. 3 and 4 shows the spring '76 to be more compressed in FIG. 4 than in FIG. 3. The rearward movement of the slide valve 72 positions the apertures or orifices 77 in communication with the chamber 83 while the orifices 78 remain in communication with the chamber 60. Thus, atomizing air bearing the accelerator from the Venturi 17 flows into the gun 1B and mixes with the control air before issuing from the nozzle 14. However, when the operative elements are in the condition illustrated in FIG. 4, there is no plaster flow inasmuch as the plaster control valve 32 is still closed and the pump 11 is still inoperative by virtue of the fact that control air is still flowing in the gun 13. This insures that there is no application of plaster before accelerator material is available for mixture therewith.

Further retraction of the trigger 51 results in the configuration of elements seen in FIG. -5. In FIG. 5, it is seen that the pin 71 now bears against the shoulder 70u and has urged the same rearwardly against the resistance of the coiled spring 56. Comparison of FIGS. 4 and 5 shows that the spring 56 has been compressed to a greater degree in FIG. 5 than in FIG. 4. It will be noted that in FIGS. 3 and 4, the spring 56 is in the same configuration. The movement of the pin 71 to the position seen in FIG. 5 results in the retraction of the valve stem 68, consequently opening the valve 32. Now the conduit 12 is open between the pump 11 and the nozzle 14. However, still no plaster is able to fiow through the conduit 12 and the L-shaped passage 30, since the pump 11 is still inoperative.

'I'he pump is finally started when the trigger is retracted to a maximum, the configuration of elements resulting therefrom being seen in FIG. 6. There it will be noted that the end 79 of the sleeve valve 72 is abutted against the rear wall 75 of the bore 57. This effectively closes off the flow of the control air from the conduit 26. Now, the air entering the chamber 21 via the conduit 20' and orifice'25 remains therein and eventually builds up sufficient pressure to overcome the resistance of the spring 24 and thereby is effective to urge the piston 22 downwardly. Downward movement of the piston 22 results in operation of `a switch (not shown) which starts the pump 11. With the trigger fully retracted, plaster fiow is initiated by the pump 11, the plaster flowing through the conduit 12, the L-shaped passage 30, and out of the nozzle 14. In so doing, the plaster passes about the valve cap 39 and becomes intimately admiXe'd with the air-borne accelerator material'delivercd to the chamber 45 through the conduit 15, the chamber 83, the apertures 77, the slide valve 72, the apertures78, the chamber '60, the axially-aligned passages -61, 48 and 47. This condition persists until pressure on the trigger 51 is released.

Release of pressure on the trigger 51 results in reversal of the just-described operation. First, the end 79 of the sleeve valve 72 is moved forwardly and away from the end wall 7 5. This results in bleeding air out of the charnber 21 and stopsthe pump 11. Further release of pressure on the trigger 51 changes the internal element configuration from that of FIG. 5 to that of FIG. 4 where the pin 71 is no longer effective to exert pressure against the shoulder 7 0a, thus resulting in the closure of the plaster valve 32. Final release of pressure from the trigger 51 results in the FIG. 3 element condition, where only control air is flowing through the gun 13 and out of the nozzle 14.

From the foregoing, it can be seen that the sequence of valve operation in the gun 113 has the following pattern: (l) Valve 72 is positioned to permit the flow of atomizing air; (2) valve 32 is positioned to permit plaster flow; (3) slide valve 72 is positioned to close off the flow of control air. Upon completion of a given plastering operation, release of pressure on the trigger 51 results in the flow of control air, the stoppage of plaster, and the stoppage of flow of the atomizing air. This sequence can be rearranged as follows: After the plaster valve 32 is opened, the valve provided by the engagement of the end 79 of the slide valve 72 with the end '75 of the bore 57 first closes, then opens. After the plaster valve 32 is closed, the valve apertures 77 are first closed relative to chamber 83, and must be opened relative thereto before the plaster valve 32 again opens.

While in the foregoing specification a detailed description of an embodiment of the invention has been set forth for the purpose of explanation, many variations in the details herein given may be seen by those skilled in the art without departing from the spirit and scope of the invention.

I claim:

1. In a spray gun for plaster and the like, a body equipped with a passage, said passage having an inlet at one end and a nozzle outlet at the other end, a valve in said passage effective to close the same and positioned adjacent to but spaced from said nozzle outlet, a second passage in said body communicating with the first-inentioned passage between said Valve and outlet, a third passage in said body communicating with said second passage, fourth and fifth passages in said body communicating with said third passage, valve means in said body operative to selectively isolate said fourth and fifth passages from said third passage, means for coupling a source of compressed air containing accelerator to said d fourth passage and a source of compressed air to said fifth passage, and trigger means coupled to said valve and valve means for first communicating said fourth and third passages and thereafter opening said valve and nally isolating said fifth and third passages.

2. In a spray gun for plaster and the like, a body equipped with a passage, said passage having an inlet at one end and a nozzle outlet at the other end, a valve in said passage effective to close the same and positioned adjacent to but spaced from said nozzle outlet, a second passage in said body communicating With the first-mentioned passage between said valve and outlet, a third passage in said body communicating with said second passage, fourth and fifth passages in said body communicating with said third passage, means for coupling a source of accelerator containing compressed air to said fourth passage and a source of compressed air to said fifth passage, and valve means in said body operative to selectively isolate said fourth and fifth passages from said third passage, said valve means including a sleeve having a pair of longitudinally spaced aperture means therein, one of said aperture means being positioned to communicate said second and third passages irrespective of the position of said sleeve, the other of said aperture means being operative to communicate said fourth and third passages in some positions of said sleeve, one end portion of said sleeve being equipped with air port means and operative to selectively communicate said fifth and third passages, said other aperture means being positioned to communicate said fourth and third passages when said air port means is operative to isolate said third and fifth passages.

3. In a spray gun, a barrel portion and a handle portion depending therefrom, a passage in said portions hav ing a generally L-shape, said passage being equipped with an inlet in said handle portion and an outlet in said barrel portion, a valve seat in said passage in the barrel portion of said gun, a valve in said passage equipped with a stem extending longitudinally of said barrel portion away from said outlet, trigger means on said gun coupled to said stem, a lost motion linkage interposed between said trigger means and stem, a fluid passage in said barrel portion communicating at one end thereof with said L-shaped passage between said valve seat and said outlet, said iiuid passage communicating at the other end thereof with a bore in said barrel portion, a slide valve in said bore coupled to said trigger means, and a pair of air inlet passages in said barrel portion communicating with said bore and selectively closed by said slide valve.

4. In a spray gun, a barrel portion and a handle portion depending therefrom, a passage in said portions having a generally L shape, said passage being equipped with an inlet in said handle portion and an outlet in said barrel portion, a valve seat in said passage in the ybarrel portion of said gun, a valve in said passage equipped with a stem extending longitudinally of said barrel portion away from said outlet, trigger means on said gun equipped with a lost motion linkage with said linkage coupled to said stem, a fiuid passage in said barrel portion communicating at one end thereof with said L-shaped passage between said valve seat and said outlet, said fluid passage communicating at the other end thereof with a bore in said barrel portion, a slide valve in said bore coupled to said trigger means, and a pair of air inlet passages in said barrel portion communicating with said bore and selectively closed -by said slide valve, one of said air inlet passages being adapted to be coupled to a source of accelerator material, said trigger means being arranged to position said slide valve for communicating said one air inlet passage with said fluid passage before opening said stemequipped valve and thereafter to position said slide valve to isolate the other of said air inlet passages from said liuid passage.

5. In plaster applying apparatus and the like, a discharge gun having a plaster inlet and outlet, a conduit in said gun communicating said inlet and outlet, a valve in said conduit, a trigger in said gun coupled to said valve for selectively opening and closing said valve, rst and' second air inlets in said gun, a passage in said gun ceupling said air inlets and communicating with said conduit between said valve and said outlet, a valve in said passage, and linkage means coupling said passage valve and trigger for controlling said passage valve means to flow air in said conduit from said iirst inlet when said trigger is retracted and from said second inlet when said trigger is unretracted.

6. In a plaster applying apparatus, a source of plaster, means for pumping plaster from said source to a discharge gun, a source of pressurized accelerator fluid, means coupling said accelerator fluid source to a first inlet in said gun, said gun comprising a body equipped with a passage for mixing said uid and plaster, a source of pressurized control iluid, conduit means coupling said control fluid source with said pumping means and a second inlet in said gun and said accelerator fluid source, and Valve means in said body for flowing said control luid therethrough from said second inlet for flushing said passage and for simultaneously stopping the flow therein of plaster and for thereafter stopping the flow therein of accelerator fluid from said first inlet.

7. The apparatus of claim 6 in which said pumping means includes a control element responsive to iluid pressure whereby said element is operative to stop said pumping means when control fluid is admitted to said passage from said second inlet by said valve means.

8. In plaster applying apparatus, a source of plaster, a pump coupled to said source, a plaster-conducting conduit coupled to said pump and terminating in a spray gun, a source of compressed air, an air-conducting conduit coupled to said compressed air source, means for introducing a liquid accelerator material into said air conduit, said air conduit also beinlg coupled to said spray gun, a second air-conducting conduit coupled to said air source and coupled to cylinder means operatively associated with said pump for actuating said pump, and a third air-conducting conduit coupling said cylinder means with said spray gun, said gun comprising a plurality of trigger actuated valves operative upon trigger retraction for first admitting accelerator material-containing air into said gun and thereafter mixing said accelerator material-containing air with plaster while simultaneously stopping the flow of flushing air from said third air conduit.

9. The apparatus of claim 8 in which said cylinder means comprises a casing equipped with a spring loaded piston, air from said second conduit being effective to overcome said spring loading when said valves are oriented to stop the ilow of flushing air.

10. The apparatus of claim 8 in which said second conduit is equipped with a constriction therein limiting the flow of air into said cylinder means to a value insuicient to overcome said spring loading when said gun valves are oriented to permit flow of ilushing air into said gun from said third conduit.

References Cited in the file of this patent UNITED STATES PATENTS 1,650,686 Binks Nov. 29, 1927 2,820,672 Arce et al. Jan. 21, 1958 '2,958,471 Zippel Nov. 1, 1960 

